Mixing and kneading device

ABSTRACT

Mixing and kneading device comprising a housing, a mixing and kneading the chamber arranged in said housing which chamber has an annular nozzle type outlet, at least one wormshaft mounted in said mixing and kneading chamber and a closure device arranged coaxially to said wormshaft adjacent to said outlet. The closure device incorporates a closure spigot and means for rotating and reciprocating the closure spigot in the longitudinal direction of the axis of said wormshaft. The plugging end of the closures is directed towards the outlet of the kneading chamber and is fitted with a tensioning device operating in the opening direction, and comes under the influence of an arrester device which opens when a predetermined axial pressure has been attained.

United States Patent MIXING AND KNEADING DEVICE 9 Claims, 3 Drawing Figs.

US. Cl 259/45, 18/2 lnt.Cl B0lf 15/02 Field of Search 259/7, 9, 10,41, 42,45,46; 18/2 (EM), 2 (EP), 2 (ES), 14

{56] References Cited UNITED STATES PATENTS 1,766,031 6/1930 Meakin 259/9 3,198,491 8/1965 Loomans 259/41X Primary Examiner-Edward L. Roberts Attorney-Abraham A. Saifitz ABSTRACT: Mixing and kneading device comprising a housing, a mixing and kneading the chamber arranged in said housing which chamber has an annular nozzle type outlet, at least one wormshaft mounted in said mixing and kneading chamber and a closure device arranged coaxially to said wormshaft adjacent to said outlet. The closure device incorporates a closure spigot and means for rotating and reciprocating the closure spigot in the longitudinal direction of the axis of said wormshaft. The plugging end of the closures is directed towards the outlet of the kneading chamber and is fitted with a tensioning device operating in the opening direction, and comes under the influence of an arrester device which opens when a predetermined axial pressure has been attained.

PATENTEB JUN 1 l97| 3; 5 2 049 SHEET 1 BF 2 Q is N w 9 I w.

INVENTORS:

Wilhelm G. WEBER and Fritz TTEB MIXING AND KNEAlDllNG navrcr:

. plastics, rubber or foodstuffs, it has been recognized that no simple, rapidly operating and reliable closure device for the outlet from the mixing and kneading chamber is commercially available. A closure device of this nature is in fact necessary to ensure that on starting up the process the mixing and kneading chamber is properly filled to carry out the desired operation, after which the outlet must be opened rapidly and completely without checking the operation or reaction.

Experiments have attempted to solve this problem by the use of a hinged hatch, a locking slide valve, an adjustable ring or ball valve but these have been only partially successful. It has not been found possible to prevent material from depositing on the closure element to clog it and in addition the rapid opening movement which is required gives rise to an asymmetrical pressurewave which leads to a breakdown of the chemical triggering reaction which is to take place in the mixing and kneading chamber. it has not been possible to solve the problem satisfactorily using throttle devices of the conventional type such as are utilized in worm extruders, since such devices employed for fine adjustment of operating pressure in the mixing chamber are incapable of rapid movement from a closed position into an open one, even if power driven and remotely controlled.

A mixing and kneading device which overcomes the disadvantages described above.

The mixing and kneading device in accordance with the invention comprises a housing, a mixing and kneading chamber arranged in said housing which chamber has an annular nozzle type outlet, at least one wormshaft mounted in said mixing and kneading chamber and a closure device arranged coaxially to said wormshaft adjacent to said outlet, said closure device incorporating a closure spigot and means for rotating and simultaneously reciprocating said closure spigot in the longitudinal direction of prolongation of the axis of said wormshaft. The plugging end of the closure is directed towards the outlet of the kneading chamber and which is fitted with a tensioning device operating in the opening direction, while influenced by an arrester device which opens when a predetermined axial pressure has been attained.

Preferably the closure device may incorporate an annular nozzle which is arranged coaxially with the wormshaft at the outlet orifice and a closure spigot mounted coaxially with the wormshaft, operating in conjunction with the annular nozzle and mounted in a housing with an outlet orifice.

The invention is illustrated in the appended drawings, in which:

H6. 1 shows a cross section through that portion of the mixing and kneading device which is fitted with the closure device,

FIG. 2 shows a cross section through an annular nozzle with rectilinear guide elements, and

FIG. 3 shows a cross section through an annular nozzle with curvilinear guide elements.

The device incorporates a housing ll7 enclosing a mixing and kneading chamber 1 in which a wormshaft 14 is mounted. At the outlet of the mixing and kneading chamber 11 an annular nozzle 2 is flange mounted coaxially to the worm shaft M. This annular nozzle 2 incorporates a cylindrical drilling which is extended conically to both ends.

To the annular nozzle 2 there is flange mounted a housing 3 which incorporates an outlet orifice 3. The housing 3 additionally incorporates a cylindrical seating for a bearing sleeve 4, a plane bearing surface for a motor 5 and a supporting arm 18 for an arrester device 6. The bearing sleeve 4 is held at one end in the housing 3 by a ring nut 4' and bears at the other end a rotatable cutter wheel 7 driven by the motor 5. In addition the bearing sleeve 4 incorporates internally two cylindrical bearing surfaces to take a closure spigot 8 and is provided with a coarse-pitched trapezoidal thread between the two bearing surfaces.

The closure spigot 8 incorporates a first cylindrically shaped portion 8 the end of which nearest the annular nozzle 2 is designed in the form ofa cone with rounded tip. At a second, medial portion 8 the closure spigot 8 is provided with a trapezoidal thread designed to complement the trapezoidal thread in the bearing sleeve 4 and engaging therein. The third portion 8" of the closure spigot 8 bears a thread on to which a nut 10 is screwed and a disc 12 with a diameter greater than that of the closure spigot and mounted on that end of it pointing away from the annular nozzle 2. Between the disc 12 and a bracket 11 fixed to the housing 3 is mounted a tensioning element in the form of a coil spring 13 which exerts a pressure on the closure spigot 8 in a direction away from the annular nozzle 2.

The nut 10 is capable of displacement in a single direction to limit the axial movement of the closure spigot and can be locked by a setscrew 15. It incorporates an annular groove 10' all round with which the pin 6' of the arrester device 6 mounted on the supporting arm 18 engages. This pin 6' is pressed by the spring 6" into the groove 10', the pressure of the spring being adjustable by means of a sleeve nut 6'.

Provided additionally on the bracket 11 is a setscrew 16 which limits adjustably the axial movement of the closure spigot in the other direction.

The annular nozzle 2 bears at its conical interior surface facing away from the outlet orifice of the mixing and kneading chamber, guide elements 9 which are wedge-shaped in cross section and arranged with tip towards the outlet orifice of the mixing and kneading chamber 1. These guide elements 9 are arranged regularly along the circumference of the conical interior surface and may be rectilinear or curvilinear in shape.

The cutter wheel 7 bears a number of blade arms 7' with adjustable blades 7". On rotation of the cutter wheel 7, the blades 7" move across the annular orifice bounded by the annular nozzle 2 and the closure spigot 8.

At the start of the operating process the closure spigot 8 is located in the position shown in P10. 1. The mixing and kneading device begins and a pressure is generated in the material in the mixing and kneading chamber ll. As soon as this has reached a certain level, the pin 6' is forced out of the groove 10' against the pressure of the spring 6" and the closure spigot 8 moves with assistance from the spring 13 away from the annular nozzle 2 into an open position. This movement not only takes place rapidly but is also overlaid with a rotating motion by the closure spigot 8, resulting in a clean separation of the rounded tip of the closure spigot 8 from the packed material.

This combined longitudinal and rotary movement is produced by the trapezoidal thread by means of which the closure spigot 8 is connected to the housing 3 and the bearing sleeve 4 respectively.

The completely mixed and kneaded material now flows out through the annular orifice bounded by the annular nozzle 2 and the closure spigot E, this annular orifice being divided up to cause the material to separate into a number of strands by the action of the guide elements 9 and the strands may if necessary be chopped by the rotating cutter wheel 7.

In order to bring the closure device back to its position of departure, i.e. to the closed position, it suffices to slide the closure spigot in the direction of the annular nozzle long enough for the pin 6' of the arrester device 6 to reengage with the groove of the nut 10. This can if desired be effected by an automatic device.

The pressure required to open the closure device can be influenced on the one hand by prestressing the spring 6 of the arrester device 6 and on the other hand by prestressing the spring 33.

The nut 10 is so adjusted that it limits the movement of the closure spigot 8 in the direction of the annular nozzle 2 in such manner that a small amount of play is retained between the conical end of the closure spigot 8 and the conical interior surface of the annular nozzle 2 to avoid the danger of the two cones seizing together. In order to fulfill the conditions demanded by certain reaction processes, both the annular nozzle 2 and the closure spigot 8 can be designed to be heated or cooled.

The mixing and kneading device described has the following special advantages:

Rapid, complete opening is achieved in association with an even distribution of pressure. The closure device is selfcleaning and the open position adjustable.

The materials of the mixed product require division into a predetermined number of material strands after issuing from the outlet of the mixing and kneading chamber which may be chopped into pieces according to requirements. This is especially necessary in the preparation of kneaded mixtures of curable plastics and also with thermoplastics, such as hard and soft PVC.

What we claim is:

l. Mixing and kneading device comprising a housing, a mixing and kneading chamber arranged in said housing which chamber has an annular nozzle outlet, at least one wormshaft mounted in said mixing and kneading chamber and a cylindrically shaped closure device with a medial threaded portion arranged coaxially to said wormshaft adjacent to said outlet, said closure device having a conical plugging end which incorporates a closure spigot, means for rotating and simultaneously reciprocating said closure spigot in the direction of the axis of said wormshaft, the plugging end of said closure device being directed towards the outlet of the kneading chamber, said spigot being fitted with a tensioning device exerting a pressure on said closure spigot in a direction away from said annular nozzle and an arrester device to limit the axial movement of the closure spigot.

2. Mixing and kneading device according to claim 1, wherein the conical end of said closure spigot which is directed toward the annular nozzle has a rounded tip, and the threaded medial portion of said closure spigot has a trapezoidal thread which engages with a corresponding trapezoidal thread in the housing so that when the closure spigot is displaced axially it is also rotated.

3. Mixing and kneading device according to claim 2, wherein a portion of the closure spigot is provided with a thread which carries a nut having an annular groove with which the arrester device engages under spring loading.

4. Mixing and kneading device according to claim 3, wherein the tensioning device at the end of the closure spigot directed away from the chamber is a coil spring which exerts a pressure on the closure spigot in the opening direction.

5. Mixing and kneading device according to claim 3 wherein said arrester device incorporates a conical-ended pin which engages the said conical end of said pin with the groove in the nut under the influence ofa spring, the prestressing of which is adjusted by means of a sleeve nut.

6. Mixing and kneading device according to claim 4, having an adjustable nut limiting the axial movement of the closure spigot and a setscrew for locking said nut.

7. Mixing and kneading device according to claim 2, wherein said annular nozzle has a cylindrical drilling bore which is extended conically towards both ends.

8. Mixing and kneading device according to claim 2, wherein said annular nozzle bears on its interior surface which is turned toward the closure spigot, rectilinear or curvilinear guide elements which are wedge-shaped in cross section and the tips of which are directed towards the mixing and kneading chamber.

9. Mixing and kneading device according to claim 1, wherein a motor-driven cutter wheel is provided in the housing, the wheel being in coaxial relation to the closure spigot and being fitted with blade arms with blades, the cutting plane of which coincides with the anterior frontal plane of the annula: nozzle. 

1. Mixing and kneading device comprising a housing, a mixing and kneading chamber arranged in said housing which chamber has an annular nozzle outlet, at least one wormshaft mounted in said mixing and kneading chamber and a cylindrically shaped closure device with a medial threaded portion arranged coaxially to said wormshaft adjacent to said outlet, said closure device having a conical plugging end which incorporates a closure spigot, means for rotating and simultaneously reciprocating said closure spigot in the direction of the axis of said wormshaft, the plugging end of said closure device being directed towards the outlet of the kneading chamber, said spigot being fitted with a tensioning device exerting a pressure on said closure spigot in a direction away from said annular nozzle and an arrester device to limit the axial movement of the closure spigot.
 2. Mixing and kneading device according to claim 1, wherein the conical end of said closure spigot which is directed toward the annular nozzle has a rounded tip, and the threaded medial portion of said closure spigot has a trapezoidal thread which engages with a corresponding trapezoidal thread in the housing so that when the closure spigot is displaced axially it is also rotated.
 3. Mixing and kneading device according to claim 2, wherein a portion of the closure spigot is provided with a thread which carries a nut having an annular groove with which the arrester device engages under spring loading.
 4. Mixing and kneading device according to claim 3, wherein the tensioning device at the end of the closure spigot directed away from the chamber is a coil spring which exerts a pressure on the Closure spigot in the opening direction.
 5. Mixing and kneading device according to claim 3 wherein said arrester device incorporates a conical-ended pin which engages the said conical end of said pin with the groove in the nut under the influence of a spring, the prestressing of which is adjusted by means of a sleeve nut.
 6. Mixing and kneading device according to claim 4, having an adjustable nut limiting the axial movement of the closure spigot and a setscrew for locking said nut.
 7. Mixing and kneading device according to claim 2, wherein said annular nozzle has a cylindrical drilling bore which is extended conically towards both ends.
 8. Mixing and kneading device according to claim 2, wherein said annular nozzle bears on its interior surface which is turned toward the closure spigot, rectilinear or curvilinear guide elements which are wedge-shaped in cross section and the tips of which are directed towards the mixing and kneading chamber.
 9. Mixing and kneading device according to claim 1, wherein a motor-driven cutter wheel is provided in the housing, the wheel being in coaxial relation to the closure spigot and being fitted with blade arms with blades, the cutting plane of which coincides with the anterior frontal plane of the annular nozzle. 